Handshaking Protocols and Jamming Mechanisms for Blind Rendezvous in a Dynamic Spectrum Access Environment

Blind frequency rendezvous is an important process for bootstrapping communications between radios without the use of pre-existing infrastructure or common control channel in a Dynamic Spectrum Access (DSA) environment. In this process, radios attempt to arrive in the same frequency channel and recognize each other’s presence in changing, under-utilized spectrum. This paper refines existing blind rendezvous techniques by introducing a handshaking algorithm for setting up communications once two radios have arrived in the same frequency channel. It then investigates the effect of different jamming techniques on blind rendezvous algorithms that utilize this handshake. The handshake performance is measured by determining the probability of a handshake, the time to handshake, and the increase in time to rendezvous (TTR) with a handshake compared to that without. The handshake caused varying increases in TTR depending on the time spent in each channel. Four different jamming techniques are applied to the blind rendezvous process: noise, deceptive, sense, and Primary User Emulation (PUE). Each jammer type is analyzed to determine how they increase the TTR, how often they successfully jam over a period of time, and how long it takes to jam. The sense jammer was most effective, followed by PUE, deceptive, and noise, respectively

A Lightweight Secure and Resilient Transmission Scheme for the Internet of Things in the Presence of a Hostile Jammer

In this article, we propose a lightweight security scheme for ensuring both information confidentiality and transmission resiliency in the Internet-of-Things (IoT) communication. A single-Antenna transmitter communicates with a half-duplex single-Antenna receiver in the presence of a sophisticated multiple-Antenna-Aided passive eavesdropper and a multiple-Antenna-Assisted hostile jammer (HJ). A low-complexity artificial noise (AN) injection scheme is proposed for drowning out the eavesdropper. Furthermore, for enhancing the resilience against HJ attacks, the legitimate nodes exploit their own local observations of the wireless channel as the source of randomness to agree on shared secret keys. The secret key is utilized for the frequency hopping (FH) sequence of the proposed communication system. We then proceed to derive a new closed-form expression for the achievable secret key rate (SKR) and the ergodic secrecy rate (ESR) for characterizing the secrecy benefits of our proposed scheme, in terms of both information secrecy and transmission resiliency. Moreover, the optimal power sharing between the AN and the message signal is investigated with the objective of enhancing the secrecy rate. Finally, through extensive simulations, we demonstrate that our proposed system model outperforms the state-of-The-Art transmission schemes in terms of secrecy and resiliency. Several numerical examples and discussions are also provided to offer further engineering insights

Master of Science

thesisCurrent approaches to secret key extraction using Received Signal Strength Indicator (RSSI) measurements mainly use the WiFi interface. However, in the presence of jamming adversaries and other interfering devices, the efficiency of RSSI-based secret key extraction using WiFi degrades and sometimes the key extraction may even fail completely. A possible method to overcome this problem is to collect RSSI measurements using the Bluetooth interface. Bluetooth appears to be very promising for secret key extraction since the adaptive frequency hopping technique in Bluetooth automatically detects and avoids the use of bad or interfering channels. In order to collect Bluetooth RSSI values, we design a protocol where Alice and Bob use Google Nexus one phones to exchange L2CAP packets and then we measure the RSSI for each received packet. We use a prequantization interpolation step to reduce the probability of bit mismatches that are caused due to the inabililty to measure the time-duplex channel simultaneously by Alice and Bob. We then use the ASBG quantization scheme followed by information reconciliation and privacy amplification to extract the secret key bits. We conduct numerous experiments to evaluate the efficiency of Bluetooth for secret key extraction under two di↵erent mobile environments - hallways and outdoors. The secret bit rates obtained from these experiments highlight that outdoor settings are better suited for key extraction using Bluetooth when compared to hallway settings. Furthermore, we show that for very small distances such as 2 ft, the number of consecutive "0" RSSI values and bit mismatch is too high to extract any secret key bits under hallway settings. Finally, we also show that Bluetooth key extraction in outdoors achieves secret bit rates that are comparable toWiFi, even when using lower transmit power than WiFi

Performance Study of Hybrid Spread Spectrum Techniques

This thesis focuses on the performance analysis of hybrid direct sequence/slow frequency hopping (DS/SFH) and hybrid direct sequence/fast frequency hopping (DS/FFH) systems under multi-user interference and Rayleigh fading. First, we analyze the performance of direct sequence spread spectrum (DSSS), slow frequency hopping (SFH) and fast frequency hopping (FFH) systems for varying processing gains under interference environment assuming equal bandwidth constraint with Binary Phase Shift Keying (BPSK) modulation and synchronous system. After thorough literature survey, we show that hybrid DS/FFH systems outperform both SFH and hybrid DS/SFH systems under Rayleigh fading and multi-user interference. Also, both hybrid DS/SFH and hybrid DS/FFH show performance improvement with increasing spreading factor and decreasing number of hopping frequencies